Method and device in the regulation of the headbox

Abstract: The invention concerns a method and a device in the regulation of the headbox. The headbox comprises a pulp (M) inlet header (10), after the pulp inlet header (10), seen in the pulp (M) flow direction, a distributor manifold (11), whose pipes (11a 1.1 ,11a 1.2 ...) are opened into an intermediate chamber (12). The headbox comprises an attenuation chamber (17) placed in connection with the intermediate chamber (12) and, after the intermediate chamber (12), a turbulence generator (13), whose tubes (13a 1.1 ,13a 1.2 ..., 13a 2.1 ,13a 2.2 ...) are opened, at their outlet end, into the discharge duct (14) and, at their inlet end, into the intermediate chamber (12). In the method, into different positions along the width of the headbox, a pulp suspension (M) flow (Q 4.1 ,Q 4.2 ...Q 4.n ) is introduced, the concentration of said flow being adjustable by means of combining of two component flows (Q₁, Q₂). In the method, in the regulation of the concentration of the flow (Q 4.1 ,Q 4.2 ...Q 4.n ) passed into the pulp suspension (M), two component flows are combined by into the pulp suspension flow (Q 3.1 , Q 3.2 ...Q 3.n ) introducing an additional flow (Q 1.1 , Q 1.2 ...Q 1.n ). In the solution, the mixing ratio of the combined flow is regulated by adjusting said additional flow (Q 1.1 ,Q 1.2 ...Q 1.n ). In the method, the additional flow (Q 1.1 ,Q 1.2 ,Q 1.3 ...Q 1.n ) is passed into the pulp (M) flow taken out of the inlet header.

Description: This invention relates to a method in the regulation of the headbox of a paper/board machine according to the preamble of claim 1. Furthermore, the invention relates to a device in the regulation of the headbox according to the preamble of claim 10. From the EP-A-0 462 472 a device in a regulation of the headbox is known which forms the basis for the preambles of the new independent claims 1 and 10. The headbox comprises an intermediate chamber from which a pulp suspension flow is passed into turbulence tubes of a turbulence generator. After the pulp suspension flow has been passed from the turbulence tubes into the discharge duct, the pulp suspension-flow is combined with an additional component flow. From the document DE 42 39 845 A1 a paper machine is known. The density of the pulp suspension flow supplied into the headbox of the paper machine is determined by combining two component flows. From the document WO 8601844 A a headbox system for a paper machine is known. In the headbox system the pulp suspensions flow is so controlled that in the event of a change on the pulp distribution over the width of the web of the web the horizontal component of the flow direction in a delivery gap remains, at all places, always in the direction of the machine. As is known from the prior art, the discharge flow of the pulp suspension out of the headbox must be of uniform velocity in the transverse direction of the paper/board machine. A transverse flow, which produces distortion of the fibre orientation, affects the quality factors of the paper produced, such as anisotropy of strength and stretch. The level and variation of anisotropy in the transverse direction also affect the printing properties of the paper. In particular, it is an important requirement that the main axes of the directional distribution, i.e. orientation, of the fibre mesh in the paper coincide with the directions of the main axes of the paper and that the orientation is symmetric in relation to these axes. At the edges of the pulp-flow duct in the headbox, a smaller amount of pulp flows. This edge effect produces a very strong linear distortion in the profile. Profile faults in the turbulence generator of the headbox usually produce a non-linear distortion in the profile inside the lateral areas of the flow ducts. Attempts are made to compensate for an unevenness of the grammage profile arising from the drying-shrinkage of paper by means of a crown formation of the slice, so that the slice is thicker in the middle of the pulp jet. When the paper web is dried, it shrinks in the middle area of the web to a lower extent than in the lateral areas, the shrinkage being, as a rule, in the middle about 4 % and in the lateral areas about 5...6 %. Said shrinkage profile produces a corresponding change in the transverse grammage profile of the web so that, owing to the shrinkage, the dry grammage profile of a web whose transverse grammage profile was uniform after the press is changed during the drying so that, in both of the lateral areas of the web, the grammage is slightly higher than in the middle area. As is known from the prior art, said grammage profile has been regulated by means of the profile bar so that the profile bar of the headbox is kept more open in the middle area than in the lateral areas. By means of said arrangement, the pulp suspension is forced to move towards the middle area of the web. Said circumstance further affects the alignment of the fibre orientation. The main axes of the directional distribution, i.e. orientation, of the fibre mesh should coincide with the directions of the main axes of the paper, and the orientation should be symmetric in relation to these axes. In said regulation of the profile bar, a change in the orientation is produced as the pulp suspension flow receives components in the transverse direction. Regulation of the lip of the headbox also produces a change in the transverse flows of the pulp jet even though the objective of the regulation is exclusively to affect the grammage profile, i.e. the thickness profile of the pulp suspension layer that is fed. Thus, the transverse flows have a direct relationship with the distribution of the fibre orientation. From the prior art, solutions of equipment are known separately by whose means attempts are made to regulate the fibre orientation, and solutions of equipment are known separately by whose means attempts are made to regulate the grammage profile of the web. However, when the grammage profile is regulated in a prior-art solution by means of the profile bar, the fibre orientation in the web is unavoidably also affected at the same time. From the prior art, a method is known in the headbox of the paper machine for the control of the distortion of the fibre orientation in the paper web. In the method, medium flows are passed into lateral passages placed at the level of the turbulence generator of the headbox, and, by regulating the magnitudes and the mutual proportions of said flows, the transverse flows of the pulp suspension are affected, and thereby the distortion of the fibre orientation is regulated. By means of the flows introduced into the lateral passages, a transverse flow velocity is produced which compensates for the distortion of the fibre orientation. On the other hand, from the applicant's FI Patent Application No. 884408 of earlier date, a method is known in the headbox of a paper machine for the control of the distribution of the fibre orientation of the paper web in the transverse direction of the machine, in which method the transverse velocity component of the discharge jet is regulated by aligning the turbulence tube of the turbulence generator. By means of the above prior-art methods for the control of the fibre orientation in the paper web, it is, as a rule, possible to control the linear distortion profiles only. The prior-art methods are suitable for the control of the fibre orientation, but, when they are used, commonly even a large non-linear residual fault remains in comparison with an even distribution of the orientation. The prior-art methods are well suitable for basic regulation of the distortion of the orientation. However, by means of the prior-art methods, it is not possible to regulate individual faults, which may occur in the orientation in the middle area of the web and which arise, e.g., from defects in the pipe system of the turbulence generator. A number of methods are also known for the regulation of the profile bar, in which cases, while the grammage profile is measured, the position of the profile bar in the headbox of the paper machine is changed and, by means of the profile bar, the thickness of the pulp suspension discharged onto the wire, and thereby, the grammage of the paper web are affected. In the way described above, said regulation, however, produces faults in the orientation, because, by means of the regulation, the flow is throttled elsewhere, whereby components of transverse velocity are produced in the flow. From the applicant's FI Patent No. 50,260 , a solution is known, in which the headbox has been divided across its width into compartments by means of partition walls and in which solution, in an individual compartment, there is at least one inlet duct for the passage of a component flow to feed diluting water into the pulp flow. The object of the present invention is to provide a method in the regulation of the headbox as well as a device in the regulation of the headbox in order to efficiently adjust the grammage profile of the paper across the width of the paper web, without deteriorating the fiber orientation profile of the paper web across the width of the paper web. This object is achieved by a combination of the features defined in the method claim 1 or by a combination of the features defined in the device claim 10. Preferred embodiments of the subject-matters of claim 1 and claim 10 are set forth in the dependent claims. According to the present invention, the consistency of the pulp suspension at different positions of width of the web can be regulated reliably so that the diluting flow remains at the position of width into which it is introduced and is not shifted in the cross direction into another compartment. Due to the inventive consistency-regulation of grammage the interdependence between the transverse grammage profile and the fibre orientation profile is eliminated. When the transverse profile of grammage is regulated by profiling the consistency, for example, when 0-water is used, the maximal amount of diluting water is 50 % of the overall flow quantity in the consistency zone. In order that this water amount should not produce transverse flows and eliminate the object of the consistency regulation, the amount of diluting water is compensated for so that the flow quantity coming from the turbulence generator is invariable in the transverse direction of the machine. The mixed/consistency-regulated flow quantity is kept invariable. In the method in accordance with the invention and in the solution of equipment in accordance with the invention, the diluting liquid is passed directly into the turbulence tube, into its mixing chamber. The introduced diluting flow displaces the pulp flow that has been introduced from the intermediate chamber and that is combined with said diluting flow by its own quantity. Thus, the sum flow remains invariable. In the following, the invention will be described with reference to some preferred embodiments of the invention illustrated in the figures in the accompanying drawing, the invention being, yet, not supposed to be confined to said embodiments alone. Figure 1A is a sectional side view of the headbox of a paper/board machine in accordance with the invention, into which 0-water is passed along a duct of its own. Figure 1B shows the area X in Fig. 1A. Figure 1C is a sectional view taken along the line I-I in Fig. 1A. The figure is an illustration partly in section. Figure 1D is a sectional view taken along the line II-II in Fig. 1A. The figure is an illustration partly in section. Figure 1E is a sectional view taken along the line III-III in Fig. 1A. Figure 2A shows the construction of the mixing chamber of a turbulence tube in the turbulence generator on an enlarged scale. Figure 2B is an enlarged sectional view taken along the line IV-IV in Fig. 2A. Figure 3 shows a second embodiment related to the mixing chamber of a turbulence tube. Figure 4A shows a third preferred embodiment of the invention related to the mixing chamber of a turbulence tube in the turbulence generator. Figure 4B is an enlarged sectional view taken along the line V-V in Fig. 4A. Figure 1A shows the headbox of a paper/board machine in accordance with the invention, which headbox comprises, proceeding in the flow direction S of the pulp suspension M, an inlet header 10, a distributor manifold 11, in which there are distributor pipes 11a 1.1 ,11a 1.2 ...,11a 2.1 ,11a 2.2 ... placed one above the other and side by side, an intermediate chamber 12, a turbulence generator 13, which comprises a number of turbulence tubes 13a 1.1 ,13a 2.1 ...,13a 1.2 ,13a 2.2 ... placed side by side and one above the other, and a discharge duct 14, into which the turbulence tubes 13a 1.1 ,13a 2.1 ...,13a 1.2 ,13a 2.2 ... of the turbulence generator 13 are opened. The discharge duct 14 is defined by a stationary lower-lip wall 15 and by an upper-lip wall 16 pivoting around an articulated joint N. In the following, when the invention is described and when a paper machine is spoken of, it is obvious that a board machine and its headbox may also be concerned. Further, the headbox in accordance with the present invention of ours comprises an attenuation chamber 17, which is opened into the intermediate chamber. The attenuation chamber 17 extends across the entire width of the machine, and the intermediate chamber 12 communicates through a duct 18 with the interior space D of the attenuation chamber 17. When the pressure in the space D is regulated, the pressure level of the pulp M present in the intermediate chamber 12 is regulated, being maintained at the invariable level determined by the attenuation chamber 17. As is shown in Fig. 1A, an overflow Q 2 is provided through the duct 18 into the attenuation chamber 17. Over the overflow threshold T, the flow Q 2 enters into the trough G and further out of the trough G through the end ducts E. The pressure is passed into the space D through the flange joint M. The equalizing chamber 17 comprises an inner pressure space D, to which a flow Q is provided for the pulp M out of the intermediate chamber 12. Pressure is introduced into the space D in the equalizing chamber 17, and the discharge of the pressure out of the space D is regulated by means of a separate valve. Thus, by means of the pressure present in the space D, the level of the pulp M passed into the equalizing chamber (flow Q 2 ) in the space D is regulated, and so also the pressure that acts further upon the pulp M in the intermediate chamber 12. At both ends of the trough G placed underneath the attenuation chamber 17, there are drain ducts E, the flow Q 2 into the equalizing chamber 17 passing further out through the trough G and back to the pulp circulation. By means of said flow Q 2 , the excess amount of the pulp M is removed from the intermediate chamber 12 that must be displaced when the diluting flow Q 1 is introduced into the mixing point in order that the combined flow Q 1 + Q 3 remains at its invariable value. Fig. 1E is a sectional view taken along the line III-III in Fig. 1A. As is shown in the figure, the equalizing chamber 17 extends across the entire machine width and, thus, from all positions of width of the equalizing chamber, there is a duct connection 18 into the intermediate chamber 12 extending across the machine width. The turbulence generator 13 is placed expressly after the intermediate chamber 12. In the solution of the present invention, a diluting flow Q 1.1 ,Q 1.2 ...Q 1.n is passed in a headbox of the sort mentioned above into the turbulence generator 13. In the solution of the present invention, each diluting flow Q 1.1 ,Q 1.2 ...Q 1.n is passed into different positions of width in the turbulence generator 13, preferably into the turbulence tubes 13a 3.1 ,13a 3.2 ...13a 3.n in the middle level, in which case, by means of the additional flow, i.e. the diluting flow Q 1.1 ,Q 1.2 ...Q 1.n , passed into the compartment formed by the tube 13a 3.1 ,13a 3.2 ...13a 3.n placed in said position of width, the grammage of the paper is regulated at the position of width concerned as said additional flow is mixed, at each particular position of width, with the pulp M, with its pulp flow Q 3.1 ,Q 3.2 ...Q 3.n , which has been passed out of the intermediate chamber 12 into the turbulence tube 13a 3.1 ,13a 3.2 ...13a 3.n in the turbulence generator 13. The turbulence generator 13 shown in Fig. 1A comprises a number of turbulence tubes placed side by side in the direction of width and in the vertical direction. The turbulence tubes 13a 3.1 ,13a 3.2 ...13a 3.n of the middle level are connected with an additional-flow duct 20a 1 ,20a 2 ...20a n , favourably a 0-water duct and favourably a pipe. Each flow duct 20a 1 ,20a 2 ... comprises a valve 21a 1 ,21a 2 ...21a n , by whose means the throttle of the additional flow Q 1.1 ,Q 1.2 ...Q 1.n is regulated and, thus, by whose means the flow velocity is regulated and the flow quantity is regulated that is passed out of the diluting-water inlet header 19 into the turbulence generator 13 into each particular compartment constituted by the tube 13a 3.1 ,13a 3.2 ...13a 3.n . When the additional flow Q 1.1 ,Q 1.2 ...Q 1.n enters into the turbulence tube 13a 3.1 ,13a 3.2 ... 13a 3.n , it is mixed in the mixing chamber 130 of the turbulence tube with the pulp M flow Q 3.1 ,Q 3.2 ...Q 3.n passed out of the intermediate chamber. In the solution in accordance with the present invention, the amount of additional flow Q 1 that is introduced is reduced from the flow quantity Q 3 of the pulp M passed out of the intermediate chamber 12. Thus, the sum flow Q 4 = Q 1 + Q 3 remains invariable during the regulation while the mixing ratio is regulated by regulation of the additional flow by means of the valve 21a 1 ,21a 2 ...21a n . The excess flow of Q 3 is passed as the flow Q 2 into the attenuation chamber D and further out of said chamber and back to the pulp circulation. Fig. 1B is a separate illustration of the area X in Fig. 1A. Into the turbulence tubes in the middle layer of the turbulence generator 13, a pulp flow Q 3 of normal concentration enters from the intermediate chamber 12 of the headbox. In the turbulence tubes in the turbulence generator 13, each additional flow Q 1 is mixed efficiently with the pulp flow Q 3 . The additional flow Q 1.1 ,Q 1.2 ...Q 1.n is passed into the mixing chamber 130 in the turbulence tubes of the turbulence generator 13. By means of the mixing chamber 130, uniform mixing of the flows Q 1 and Q 3 is permitted, and the uniform pressure maintained in the intermediate chamber 12 is passed to the mixing point. The quantity of the combined flow Q 1 + Q 3 remains invariable, while the mixing ratio is regulated by means of the additional flow Q 1 . In the embodiment of the figure, the middle layer in the turbulence generator is the layer that is used as the regulation layer, in which the additional flow, favourably a water flow, and the flow of the pulp (M) of average concentration coming out of the intermediate chamber 12 are combined. In such a case, the flow of regulated concentration is passed through the turbulence generator 13, and said flow Q 4.1 , Q 4.2 ...Q 4.n joins, in the vertical direction, the other, non-regulated flows of the pulp (M) coming out of the other tubes in the turbulence generator, while, at each position of width of the web, the middle layer operates as the layer that regulates the grammage of the web. The headbox in accordance with the invention is regulated so that, during operation, the grammage is regulated expressly by means of regulation of the additional flow Q 1.1 ,Q 1.2 ...Q 1.n . Thus, during running, the profile bar is not displaced and, thus, the systems of control and monitoring of the profile bar K are not maintained then. If there is a profile bar K, it is used just at the beginning of the run for advance regulation of the fibre orientation. The profile bar is never used for regulation of the grammage. The profile bar K comprises adjusting spindles with infrequent spacing and manual operation. The additional flow Q 1 is favourably a flow that contains water alone or a so-called 0-water flow. The additional flow Q 1 may also be a pulp flow whose concentration differs, on the whole, from the average concentration of the pulp suspension in the headbox and, thus, from the concentration of the flow Q 3 . Fig. 1C is a sectional view taken along the line I-I in Fig. 1A. Each additional-flow duct 20a 1 ,20a 2 ..., preferably a pipe, comprises a valve 21a 1 ,21a 2 ..., in which case it is possible, in the direction of width of the paper machine, to adjust the desired mixing ratio for the flows Q 4.1 ,Q 4.2 ...Q 4.n at each position of width, which flow, as it comes out of the turbulence generator 13 out of its turbulence tube 13a 1 ,13a 2 ..., acts further as a regulation flow at the desired location of width of the pulp suspension jet. Fig. 1D is a sectional view taken along the line II-II in Fig. 1A. Out of the diluting inlet header 19, the diluting liquid, preferably diluting water, is passed into the duct 20a 1 ,20a 2 ..., and by means of the valve 21a 1 ,21a 2 ... placed in each duct, preferably a pipe, said diluting flow is regulated by throttling said flow in accordance with the regulation of the valve. Fig. 1E is a sectional view of the attenuation chamber 17 shown in Fig. 1A. As is shown in the figure, the attenuation chamber 17 extends across the entire machine width. Fig. 2A is an enlarged illustration of the solution shown in Fig. 1B. From the intermediate chamber 12, a flow Q 3.1 passes into the mixing chamber 130 in the turbulence tube 13a 3.1 of the turbulence generator 13. Into said mixing chamber, a flow duct 20a 1 is provided for the diluting flow. In the embodiment of Fig. 2A, the flow duct joins the mixing chamber halfway in relation to the length of the mixing chamber. The sectional flow area of the mixing chamber 130 in the direction of the flow S (arrow S) is A 1 , and this area is substantially larger than the sectional flow area A 2 of the duct portion 131 following after the mixing chamber in the turbulence tube in the turbulence generator. Figure 2B is a sectional view taken along the line IV-IV in Fig. 2A. Fig. 3 shows a second preferred embodiment of the construction related to the mixing chamber. The flange piece 1320 comprises a flow duct 132. The flow duct 132 comprises a straight duct portion 132a 1 of circular section and therein a sectional flow area A 3 and a conically widening duct portion 132a 3 , which is connected with the walls 130' of the mixing chamber 130. The flow duct 132 is placed between the intermediate chamber 12 and the mixing chamber 130. The sectional flow area A 3 is substantially smaller than the sectional flow area A 1 of the mixing chamber 130. The flange piece 1320 is connected, by means of a press fitting or a threaded joint, with the recess f 1 that has been made into the face of the frame 13R of the turbulence generator 13 defined by the intermediate chamber 12. Also in this embodiment, the mixing chamber 130 is followed by a duct portion 131 in the turbulence tube, whose sectional flow area is substantially smaller than the sectional flow area of the mixing chamber 130. Fig. 4A shows an embodiment related to the mixing chamber, wherein a pipe or duct 133 extends from the intermediate chamber 12 into the mixing chamber 130. The pipe 133 extends into the mixing chamber 130 so that the pipe is opened in the end of the mixing chamber 130 and is placed centrally on the central axis X 1 of the mixing chamber 130. The flow Q 3 from the intermediate chamber 12 enters through the pipe 133 into the mixing chamber 130. On its outer face 133', the pipe 133 comprises a throttle flange 133d, preferably an annular flange, which projects from said outer face and by whose means the diluting flow Q 1 is throttled. The annular flange 133d is placed on the circular circumference of the pipe 133. The diluting flow Q 1.1 is passed into the space between the pipe 133 face 133' and the mixing-chamber 130 face 130', in the way shown in Fig. 4, along two diluting ducts 20a 1 ', 20a 1 . Of course, there may be just one diluting-flow duct. In view of considerations of space, it is possible to use two ducts in the way shown in Fig. 4. Also, the pipe 133 comprises a flange 133c, preferably an annular flange, at its end, by means of which flange the pipe is connected with the recess f 2 in the frame 13R of the turbulence generator. The joint is accomplished either by means of a press fitting or by means of a threaded joint. It can also be accomplished by gluing. The front face of the flange 133c is placed facing the intermediate chamber 12. Fig. 4B is a sectional view taken along the line V-V in Fig. 4A. The flow Q 1 out of the additional-flow duct 20a 1 passes annularly to the end of the pipe 133 bypassing the flange 133d of the pipe. The flows Q 3 and Q 1 are combined in the mixing chamber 130 at the end of the pipe 133.

Claims: A method in the regulation of the headbox, which headbox comprises a pulp inlet header (10), after the pulp inlet header (10), seen in the pulp flow direction, a distributor manifold (11) whose pipes (11a 1.1 , 11a 1.2 ...) are opened into an intermediate chamber (12), and the headbox comprising an attenuation chamber (17) placed in connection with the intermediate chamber (12) and, after the intermediate chamber (12) a turbulence generator (13) whose tubes (13a 1.1 , 13a 1.2 ..., 13a 2.1 , 13a 2.2 ...) are opened at their outlet end into the discharge duct (14) and at their inlet end into the intermediate chamber (12), in which method a pulp suspension flow (Q 4.1 , Q 4.2 ...Q 4.n ) is introduced into different positions along the width of the headbox, the concentration of said flow being adjustable by means of combining two component flows (Q 1 , Q 3 ), characterized in that the two component flows (Q 1 , Q 3 ) are combined by introducing an additional flow (Q 1.1 , Q 1.2 ...Q 1.n ) into the pulp suspension flow (Q 3.1 , Q 3.2 ...Q 3.n ), wherein the mixing ratio of the combined flow is regulated by adjusting said additional flow (Q 1.1 ,Q 1.2 ...Q 1.n ), and the additional flow (Q 1.1 , Q 1.2 ,Q 1.3 ...Q 1.n ) is passed into the turbulence generator (13) into its turbulence tubes (13a 3.1 , 13a 3.2 ...13a 3.n ) placed at different positions of width. Method as claimed in claim 1, characterized in that the mixing ratio of the combined flow is regulated by regulating said additional flow (Q 1.1 , Q 1.2 ...Q 1.n ) by reducing or increasing the throttle of said additional flow by means of a valve (21a 1 , 21a 2 ..21a n ). Method as claimed in claim 1, characterized in that, in the method, out of the intermediate chamber (12), into the turbulence tubes (13a 3.1 , 13a 3.2 ...) of the turbulence generator (13), a pulp flow (Q 3.1 ,Q 3.2 ...) is passed, whose concentration corresponds to the average concentration of the pulp suspension in the headbox, and that the additional flow (Q 1.1 ,Q 1.2 ...) consist of a water flow, which is combined with the pulp flow (Q 3.1 ,Q 3.3 ...Q 3.n ) in the turbulence tube (13a 3.1 ,13a 3.2 ...13a 3.n ) of the turbulence generator (13). Method as claimed in any of the preceding claims, characterized in that, in the method, an additional flow (Q 1.1 ,Q 1.2 ...Q 1.n ) is passed out of its inlet header (19) into the additional-flow pipe (20a 1 ,20a 2 ...20a n ) placed in each of the different positions of width of the headbox. Method as claimed in any of the preceding claims, characterized in that an additional flow (Q 1.1 ,Q 1.2 ...Q 1.n ) is passed in the turbulence generator (13) into the mixing chamber (130) of the turbulence tube (13a 3.1 , 13a 3.2 ...13a 3.n ), which mixing chamber (130 communicates with the intermediate chamber (12), and that the combined flow (Q4 = Q1+ Q3) is passed from the mixing chamber (130) into a duct portion (131) whose sectional flow area (A2) is smaller than the sectional flow area (A1) of the mixing chamber (130). Method as claimed in claim 5, characterized in that the flow (Q 3 ) is passed out of the intermediate chamber (12) into the mixing chamber of the turbulence generator (13) through a duct portion (132) whose sectional flow area (A 3 ) is substantially smaller than the sectional flow area (A 1 ) of the mixing chamber (130). Method as claimed in claim 1, characterized in that the diluting flow (Q 1 ) is passed into the turbulence generator (13) so that it is passed into the mixing chamber (130) of the turbulence tube (13a 3.1 , 13a 3.2 ...13a 3.n ), which mixing chamber is placed at the inlet end of the turbulence tube (13a 3.1 , 13a 3.2 ...13a 3.n ) and which mixing chamber (130) has a sectional flow area (A 1 ) larger than the sectional flow area (A 2 ) of the subsequent duct portion (131), and that the pulp flow (Q 3 ) out of the intermediate chamber (12) is passed through a separate pipe (133) into said mixing chamber (130) in the turbulence tube, the inlet end of said pipe (133) opening into the intermediate chamber (12), and the outlet end of said pipe (133) opening into the mixing chamber (130), and the diluting flow (Q 1.1 , Q 1.2 ...Q 1.n ) being passed annularly from around said pipe into the end of the mixing chamber (130), in which the pulp flow (Q 3.1 , Q3 .2 ...Q 3.n ) coming out of the intermediate chamber and the diluting flow (Q 1.1 , Q 1.2 ...) passed out of the diluting inlet header (19) are mixed together, the combined flow (Q 4.1 ,Q 4.2 ...Q 4.n ) being passed into the discharge duct (14). Method as claimed in the preceding claim, characterized in that the end of the pipe (133) passed from the intermediate chamber (12) comprises a flange (133d) or equivalent which projects from the face plane (133') of the pipe and by whose means the diluting flow (Q 1.1 , Q 1.2 ...) is throttled before it is mixed with the pulp flow (Q 3.1 ,Q 3.2 ...) passed out of the intermediate chamber (12). Method as claimed in any of the preceding claims, characterized in that the grammage of the web is regulated exclusively by regulating the additional flow (Q 1.1 , Q 1.2 ...Q 1.n ), regulation and monitoring of the profile bar (K) during running being not used. A device in the regulation of the headbox, which headbox comprises, in the flow direction of the pulp flow (M), a pulp inlet header (10), and a distributor manifold (11) whose distributor pipes (11a 1.1 ,11a 1.2 ...11a 2.1 , 11a 2.2 ...11a n.1 ,11a n.2 ...) are opened into an intermediate chamber (12) which comprises, in its connection, an attenuation chamber (17) by means of which the pressure of the pulp (M) present in the intermediate chamber (12) is regulated, and which is followed by a turbulence generator (13) whose turbulence tubes (13a 3.1 , 13a 3.2 ...13a 3.n ) are opened into the discharge duct (14), wherein a flow (Q 4.1 Q 4.2 ...Q 4.n ) is introduced into the pulp suspension (M) of the headbox, the grammage of the paper being adjustable to the desired level across the web width by means of regulation of the concentration of said flow (Q 4.1 ,Q 4.2 ...Q 4.n ), wherein the flow (Q 4.1 ,Q 4.2 ...) passed into the pulp suspension (M) is composed of at least two component flows (Q 3.1 ,Q 3.2 ...;Q 1.1 ,Q 1.2 ...), said device comprising additional flow ducts (20a 1 ,20a 2 ...20a n ) in different positions of width in the headbox, through which ducts an additional flow (Q 1.1 ,Q 1.2 ...Q 1.n ) is introduced into the pulp suspension flow (Q 3.1 ,Q 3.2 ....Q 3.n ), the additional flow ducts (20a 1 ,20a 2 ...) communicating with some system of pipes of the pulp flow passed out of the pulp inlet header, characterized in that the additional flow ducts (20a 1 ,20a 2 ...) communicate with the turbulence tubes (13a 3.1 ,13a 3.2 ...13a 3.n ) of the turbulence generator (13), respectively. Device as claimed in the preceding claim, characterized in that the additional flow (Q 1.1 ,Q 1.2 ...Q 1.n ) can be passed into different positions of width in the turbulence generator (13), in which case it is possible to regulate the additional flow (Q 1.1 ,Q 1.2 ...Q 1.n ) passed into each position of width, and that the turbulence tube (13a 3.1 ,13a 3.2 ...13a 3.n ) in the turbulence generator (13) into which the additional flow is introduced comprises a mixing chamber (130), to which the additional-flow duct (20a 1 ,20a 2 ...) is connected. Device as claimed in any of the preceding claims 10 or 11, characterized in that the additional flow ducts (20a 1 ,20a 2 ...) comprise a valve (21a 1 ,21a 2 ...) that regulates the flow, by means of which valve the flow resistance and, thus, the flow quantity of the additional flow (Q 1.1 ,Q 1.2 ...) are regulated. Device as claimed in any of the preceding claims 10 to 12, characterized in that the mixing chamber (130) of the turbulence tube (13a 3.1 ,13a 3.2 ...13a 3.n ) of the turbulence generator (13) comprises, in the flow direction (S) of the pulp flow, a sectional flow area (A 1 ) which is substantially larger than the sectional flow area (A 2 ) of the duct portion (131) following after the mixing chamber, the diluting flow (Q 1.1 , Q 1.2 ...) and the pulp flow (Q 3.1 ,Q 3.2 ...) passed out of the intermediate chamber (12) being mixed together efficiently by means of the mixing chamber (130) so that the additional flow (Q 1.1 , Q 1.2 ...) ends up expressly in the tube (13a 3.1 ,13a 3.2 ...13a 3.n ) in the turbulence generator (13) with which it is connected, and in said tube further. Device as claimed in any of the preceding claims 10 to 13, characterized in that, between the mixing chamber (130) and the intermediate chamber (12) of the headbox, there is a flow duct portion (132) of a smaller sectional flow area (A 3 ), in comparison with the sectional flow area (A 1 ) of the mixing chamber (130). Device as claimed in the preceding claim, characterized in that there is a separate flange piece (132) which comprises a throttle-duct portion (132) and which is mounted by means of a threaded joint or by means of a press fitting at the mouth of the turbulence tube (13a 3.1 ,13a 3.2 ...13a 3.n ) concerned in the turbulence generator (13). Device as claimed in the preceding claim, characterized in that the throttle piece (1320) comprises at least two duct portions: a straight duct portion (132a 1 ), which has an invariable sectional flow area (A 3 ), and a conically widening duct portion (132a 2 ), which is connected with the walls (130') of the mixing chamber (130). Device as claimed in any of the preceding claims 10 to 16, characterized in that the mixing chamber (130) of the turbulence tube (13a 3.1 ,13a 3.2 ...13a 3.n ) comprises a pipe (133) passed into said chamber from the intermediate chamber (12) of the headbox, the diluting flow (Q 1.1 , Q 1.2 ...) being passed annularly between the outer face (130') of the mixing chamber (130) and said pipe (133) into the mixing point placed at the end of the pipe (133) in the mixing chamber (130) of the turbulence tube in the turbulence generator and, being hereupon combined with the flow (Q 3.1 ,Q 3.2 ...), said flows are passed further, and that said pipe (133) is opened, at the inlet end of the flow (Q 3 ), into the intermediate chamber (12), and at the other end into the turbulence tube (13a 3.1 , 13a 3.2 ...13a 3.n ), into the mixing chamber (130) at its inlet end. Device as claimed in any of the preceding claims 10 to 17, characterized in that the pipe (133) comprises a flange (133c), which is connected with a recess (f 2 ) in the front face at the inlet-side end of the turbulence generator, said flange (133c) being placed facing the intermediate chamber (12). Device as claimed in claim 17 or 18, characterized in that , at its outlet end, the pipe (133) comprises a throttle flange (133d) or equivalent, by whose means the diluting flow (Q 1 ) is throttled before the point of mixing of the flows (Q 1 and Q 3 ). Device as claimed in any of the preceding claims 10 to 19, characterized in that two additional-flow pipes (24a 1 ,24a 1 ') are opened into the mixing chamber (130), an additional flow being passed through both of said pipes into the mixing chamber to be mixed together with the pulp flow (Q 3 ) of the pulp (M). Device as claimed in any of the preceding claims 10 to 20, characterized in that the additional-flow pipe (20a 1 ) is connected to the turbulence tube (13a 3.1 , 13a 3.2 ...13a 3.n ) of the turbulence generator substantially perpendicularly, whereby the additional flow (Q 1.1 , Q 1.2 ...) and the connecting pulp (M) flow (Q 3.1 ,Q 3.2 ...) meet each other substantially perpendicularly.

Inventors: HUOVILA JYRKI, LINSURI ARI, NYBERG PETRI, ODELL MICHAEL, HUOVILA, JYRKI, LINSURI, ARI, NYBERG, PETRI, ODELL, MICHAEL
Applicants: METSO PAPER INC, METSO PAPER, INC.
Application year: 1994
Main classification: D21F1
IPC codes: D21F1